I have seen a few "kits" for $900-1500, but I'm not prepared to dump that much into a printer that looks like it was built from tinker toys. Since I'm going to the effort of gathering parts myself, I would like to experiment with different designs/materials. This way, there is a greater chance of using things I already have and I don't have to get printed reprap parts.

Towards that end, I have some nice glass sheets salvaged from an old copier. I'm wondering if anyone has tried glass as a print bed material or if it even makes sense to try it. I have seen some aluminum print beds, so apparently the bond between rafts and the print bed doesn't depend entirely on melting to the print bed? The glass is the smoothest, most perfectly flat material I have on hand. Assuming a raft could adhere to it, it seems like a plausible material. If it sticks too well, getting the part off without breaking the glass could be a problem. As a salvaged item, I wouldn't mind that risk though. Glass also conducts heat (though, maybe not as well as aluminum), so it might be interesting to try making a heated print bed from it.

Is it even worth trying? Has anyone every actually used a glass print bed?

I have a repstrap that has a glass plate as the print bed. I have not printed directly on it, though. I have printed these ways:

1. ABS on plexiglass sheet taped to the glass at the corners. The plexiglass has to be at least 1/4" or the ABS will bend it considerably.
2. PLA on foam board taped to the glass. This was marginal. The slight warping that PLA does was enough to overcome the stiffness of the foamboard.
3. PLA on blue "clean release" tape on the glass. This worked pretty well.

I am afraid that the ABS or PLA will not stick to the glass well enough (though hot glass might work better). If you do it, try with something small.

I would suggest that you use 3/8" thick plexiglass. It is easier to attach hardware to than glass is (easier to drill holes).

fdavies

I print pla onto masking tape, so you could just cover the glass print area in tape. You'd maintain flatness, and masking tape is a good balance of being sticky enough to not peel and warp, but can be easily removed. Glass is a pretty lousy conductor of heat, so you should use a fairly even heat source.